// default color
import { Message } from 'element-ui'
import varcss from '@styles/variable.scss'
const version = require('element-ui/package.json').version // element-ui version from node_modules
const ORIGINAL_THEME = '#409EFF'
class Theme {
  constructor(val) {
    this.theme = val
    this.setThemeVal(val)
    this.chalk = ''
    /**
   * 根据当前的背景颜色确认适合背景色的文本颜色 (黑 和 白)
   * 场景: 适用于标签等用户自己定制颜色，文本颜色自适应
   */

    this.colorByBgColor = new Map()
    this.rgbRegex = /^rgb\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\)$/
    this.hex = (x) => ('0' + parseInt(x).toString(16)).slice(-2)
    this.CACHE_ERROR = 'error'
  }

  async setThemeVal (val) {
    const oldVal = this.chalk ? this.theme : ORIGINAL_THEME
    if (typeof val !== 'string') return
    const themeCluster = this.getThemeCluster(val.replace('#', ''))
    const originalCluster = this.getThemeCluster(oldVal.replace('#', ''))

    const $message = Message({
      message: '  Compiling the theme',
      customClass: 'theme-message',
      type: 'success',
      duration: 0,
      iconClass: 'el-icon-loading'
    })

    const getHandler = (variable, id) => {
      return () => {
        const originalCluster = this.getThemeCluster(ORIGINAL_THEME.replace('#', ''))
        const newStyle = this.updateStyle(this[variable], originalCluster, themeCluster)

        let styleTag = document.getElementById(id)
        if (!styleTag) {
          styleTag = document.createElement('style')
          styleTag.setAttribute('id', id)
          document.head.appendChild(styleTag)
        }
        styleTag.innerText = newStyle
      }
    }

    if (!this.chalk) {
      const url = `https://unpkg.com/element-ui@${version}/lib/theme-chalk/index.css`
      await this.getCSSString(url, 'chalk')
    }

    const chalkHandler = getHandler('chalk', 'chalk-style')

    chalkHandler()

    const styles = [].slice.call(document.querySelectorAll('style'))
      .filter(style => {
        const text = style.innerText
        return new RegExp(oldVal, 'i').test(text) && !/Chalk Variables/.test(text)
      })
    styles.forEach(style => {
      const { innerText } = style
      if (typeof innerText !== 'string') return
      style.innerText = this.updateStyle(innerText, originalCluster, themeCluster)
    })
    this.contrastTextColor(val)
    $message.close()
  }

  updateStyle (style, oldCluster, newCluster) {
    let newStyle = style
    oldCluster.forEach((color, index) => {
      newStyle = newStyle.replace(new RegExp(color, 'ig'), newCluster[index])
    })
    return newStyle
  }

  getCSSString (url, variable) {
    return new Promise(resolve => {
      const xhr = new XMLHttpRequest()
      xhr.onreadystatechange = () => {
        if (xhr.readyState === 4 && xhr.status === 200) {
          this[variable] = xhr.responseText.replace(/@font-face{[^}]+}/, '')
          resolve()
        }
      }
      xhr.open('GET', url)
      xhr.send()
    })
  }

  getThemeCluster (theme) {
    const tintColor = (color, tint) => {
      let red = parseInt(color.slice(0, 2), 16)
      let green = parseInt(color.slice(2, 4), 16)
      let blue = parseInt(color.slice(4, 6), 16)

      if (tint === 0) { // when primary color is in its rgb space
        return [red, green, blue].join(',')
      } else {
        red += Math.round(tint * (255 - red))
        green += Math.round(tint * (255 - green))
        blue += Math.round(tint * (255 - blue))

        red = red.toString(16)
        green = green.toString(16)
        blue = blue.toString(16)

        return `#${red}${green}${blue}`
      }
    }

    const shadeColor = (color, shade) => {
      let red = parseInt(color.slice(0, 2), 16)
      let green = parseInt(color.slice(2, 4), 16)
      let blue = parseInt(color.slice(4, 6), 16)

      red = Math.round((1 - shade) * red)
      green = Math.round((1 - shade) * green)
      blue = Math.round((1 - shade) * blue)

      red = red.toString(16)
      green = green.toString(16)
      blue = blue.toString(16)

      return `#${red}${green}${blue}`
    }

    const clusters = [theme]
    for (let i = 0; i <= 9; i++) {
      clusters.push(tintColor(theme, Number((i / 10).toFixed(2))))
    }
    clusters.push(shadeColor(theme, 0.1))
    return clusters
  }

  convertRGBToHex (rgb) {
    const bg = rgb.match(this.rgbRegex)
    if (!bg) {
      return ''
    }
    return ('#' + this.hex(bg[1]) + this.hex(bg[2]) + this.hex(bg[3])).toUpperCase()
  }


  /**
 * @param backgroundColor 字符串  #FFFBBC | rgb(222,33,44) 均可
 */
  contrastTextColor (backgroundColor) {
    const cacheColor = this.colorByBgColor.get(backgroundColor)
    if (cacheColor) {
      if (cacheColor === this.CACHE_ERROR) {
        throw new Error('Invalid background color.' + backgroundColor)
      }
      return this.colorByBgColor.get(backgroundColor)
    }

    // 均转换为 hex 格式
    const backgroundHexColor = backgroundColor.length > 7 ? this.convertRGBToHex(backgroundColor) : backgroundColor

    let hex = backgroundHexColor
    if (hex.startsWith('#')) {
      hex = hex.substring(1)
    }
    if (hex.length === 3) {
      hex = [hex[0], hex[0], hex[1], hex[1], hex[2], hex[2]].join('')
    }

    if (hex.length !== 6) {
      this.colorByBgColor.set(backgroundColor, this.CACHE_ERROR)
      throw new Error('Invalid background color.' + backgroundColor)
    }

    const r = parseInt(hex.slice(0, 2), 16)
    const g = parseInt(hex.slice(2, 4), 16)
    const b = parseInt(hex.slice(4, 6), 16)

    if ([r, g, b].some(x => Number.isNaN(x))) {
      this.colorByBgColor.set(backgroundColor, this.CACHE_ERROR)
      throw new Error('Invalid background color.' + backgroundColor)
    }

    const textColor = (r * 0.299 + g * 0.587 + b * 0.114) > 186 ? varcss.gray600 : '#fff'
    this.colorByBgColor.set(backgroundColor, textColor)

    // const head = document.getElementsByTagName('head')[0]
    // const style = document.createElement('style')
    // style.type = 'text/css'
    // head.appendChild(style)
    // if (style.styleSheet) {
    //   style.styleSheet.cssText = `.el-button--primary{color:${textColor}!important;}`
    // } else {
    //   style.appendChild(document.createTextNode(`.el-button--primary{color:${textColor}!important;`))
    // }
    // head.appendChild(style)
    return textColor
  }
}

export default Theme
